Alkylene oxide such as ethylene oxide is typically produced in an oxidation reactor by a silver catalyzed, vapor phase, partial oxidation of ethylene with molecular oxygen which results in a gaseous reaction effluent. However, the gaseous reaction effluent can be extremely dilute with respect to the desired ethylene oxide content, containing for example, from about 0.3 mole percent to about 5 mole percent of ethylene oxide. In addition, the gaseous reaction effluent can further contain undesirable components such as acetaldehyde and formaldehyde that can be formed in the oxidation reactor or downstream to the oxidation reactor.
Recovery of the ethylene oxide from the gaseous reaction effluent can involve an initial water absorption step, followed by a stripping step, which is in turn followed by a reabsorption step. In some instances, each of the steps is carried out in separate distillation columns, which can lead to high equipment costs and safety concerns where areas of concentrated vapor phase or liquid phase ethylene oxide exist. One exemplary area where concentrated liquid phase ethylene oxide can exist is when vapor phase ethylene oxide coming out of the top of an ethylene oxide stripper is condensed, giving liquid ethylene oxide. The liquid ethylene oxide produced in the stripper can be transported to another piece of equipment to be further refined. However, handling and/or transporting concentrated ethylene oxide, for example, liquid ethylene oxide, can be dangerous due to the risk of contamination since contaminated liquid ethylene oxide can lead to a runaway polymerization which generates heat and can be explosively violent. As such, avoiding and/or alleviating the areas of concentrated and/or contaminated liquid ethylene oxide can increase safety in the recovery of ethylene oxide.
For applications requiring higher ethylene oxide product purity the ethylene oxide has to be further refined. Typically the ethylene oxide product recovered can undergo a number of distillation steps which can again adversely affect the production economics. Thus an improved system and process for recovery of alkylene oxide from an aqueous mixture containing ethylene oxide is desirable. An improved system for recovery of alkylene oxide may avoid or alleviate some of the issues presently associated with alkylene oxide recovery.